The invention relates to an apparatus for the volumetric dosing of viscous products. More specific the invention relates to an apparatus for the volumetric dosing of aerated and therefore compressible, viscous products such as ice-cream.
In the dosing of viscous products it is often desired to use the so-called bottom-up filling method in order to avoid inclusion of air pockets. This method involves the upwards movement of the dispensing outlet during the dispensing period, thereby maintaining a relatively small distance between the product level in the container to be filled and the dispensing outlet.
Existing bottom-up fillers, especially when used for filling ice-cream, are inflexible in that the volume of the product to be dispensed can hardly be varied within a short time. Additionally the dosing accuracy is generally rather low and sensitive to the pressure in the supply conduit. Furthermore the dead volume of these devices is rather high, which also increases inaccuracy.
It is an object of the present invention to provide an apparatus for the accurate volumetric dosing of viscous products of the bottom-up filler type, which is easy to operate, which is flexible and which is less sensitive to the compressibility of the product, and which avoids the effects of post-expansion in the dispensing tube due to its dead volume.
It has been found that such a filling device advantageously comprises a vertically moveable dispensing outlet and a dosing chamber, wherein the moveable part of the dispensing outlet constitutes the lower end of the dosing chamber. An apparatus according to the invention is therefore characterized by a supply conduit, a valve for said supply conduit, a dosing chamber, a dispensing outlet which constitutes the lower end of the dosing chamber, a valve for said outlet and means for substantially vertically moving said outlet.
Preferably the dispensing device comprises a housing for substantially vertically guiding the movement of the dispensing outlet. This housing can also constitute the side wall of the dosing chamber. Preferably the housing also guides the movement of those parts which constitutes the supply valve and/or the dispensing valve.
In an advantageous embodiment of a device according to the invention there are provided means for sucking back a part of the product after dispensing to prevent dripping and trailing of the product during withdrawal of the dispensing outlet of the product during non-dispensing. An example of such a suction device is disclosed in EP No. 142 204.
Preferably the suction means are constituted by the parts which also constitute the supply valve and/or the upper wall of the dosing chamber.
The invention also provides a method for the dosing of viscous products using a dispensing device comprising a supply conduit, a supply valve, a dosing chamber, a dispensing outlet which constitutes the lower end of the dosing chamber, a dispensing valve and means for substantially vertical moving said outlet, comprising the steps of;
(a) downwardly moving the dispensing outlet while the supply valve is open and the dispensing valve is closed, thereby increasing the volume of the dosing chamber and filling the dosing chamber with viscous product PA1 (b) closing the supply valve PA1 (c) opening the dispensing valve PA1 (d) upwardly moving the dispensing outlet, thereby decreasing the volume of the dosing chamber and ejecting the viscous product from the dosing chamber PA1 (e) closing the dispensing valve, and PA1 (f) opening the supply valve.
Preferably the closing of the supply valve under (b) is effected by downwardly moving the parts which constitute the upper end of the dosing chamber. This downward movement is preferably accompanied by a further equal downward movement of the dispensing outlet to ensure a constant volume of the dosing chamber to avoid compression of its contents.
The upward movement of the dispensing outlet may be accompanied by an upward or downward movement of the upper end of the dosing chamber, as long as the desired changed volume of the dosing chamber is effected. An upward movement of the upper end of the dosing chamber will generally reduce the dispensing rate, a downward movement will increase the dispensing rate.
Between steps (d) and (e) it is also possible to effect an upward movement of the upper end of the dosing chamber in relation to the dispensing outlet while the dispensing valve is still open, thereby effecting a sucking back of material from the dispensing outlet into the dosing chamber and the supply conduit.